1. Field of the Invention
The present invention relates to a noise filter device.
2. Description of the Related Art
A vehicle-mounted noise filter device is required to be small in size and light in weight due to the restriction of an installation space thereof. WO 2007/020902 discloses a noise filter device having an enhanced noise removal ability by adopting a π-type filter circuit using a pair of capacitors and a coil while realizing a small size and a high heat radiation property.
However, the π-type filter circuit has a problem that electric field coupling is caused if the capacitors are close to each other and a noise removal characteristic is reduced due to the generation of a coupling capacitance. Further, if the capacitors are distanced from each other to suppress electric field coupling, there is a problem of enlarging the noise filter device.
The present invention was completed based on the above situation and aims to provide a noise filter device that is small in size and suppresses electric field coupling.